PLANTS FROM ALASKA. 159 



to have been a raised cord-like line, running down the center of their 

 upper surface. The primary pinnse of this specimen go off from the 

 main rachis opposite to one another. PI. XL, Fig. 2, shows two of the 

 pinnules enlarged. Another specimen, which is given in PI. XL, Fig. 3, 

 seems to belong to a position nearer the end of the compound pinna than 

 the part represented in Fig. 1. It is also a portion of an antepenultimate 

 pinna. In this the ultimate pinnae are much reduced in size, and the 

 same is true of the pinnules. The latter are more united and tend to 

 pass to lobes and teeth. Many of the pinnules and lobes in this form 

 are much mutilated and do not show their true shape. PI. XL, Fig. 4, 

 shows the lower part of a pinnule enlarged. The form given in PI. >XL, 

 Fig. 5, probably represents a stage between these two. This gives one 

 of the penultimate pinnae more complete. PI. XL, Fig. 6, shows a pinnule 

 enlarged. PL XXXIX, Fig. 9, probably represents a portion of a penul- 

 timate pinna from lower down on the compound pinna than any of 

 those shown in PI. XL, Fig. 1. In this the pinnules are more separated 

 than in any of the other specimens. They are also larger, and the largest 

 of them show serrate teeth. These can be seen distinctly only with the 

 help of a lens. They are shown in the magnified pinnule, PI. XXXIX, 

 Figs. 10 and 11. It is probable that still lower down the teeth become 

 more pronounced and take the character shown in Cladophlebis alata. 



This plant seems to be identical with two ferns first found in the 

 Potomac, or Lower Cretaceous formation. They are Cladophlebis alata 

 and Pecopteris strictinervis. These specimens make it most probable 

 that the two ferns from the lower Potomac of Virginia, called by the 

 present writer Cladophlebis alata and Pecopteris strictinervis, are the 

 same. Pecopteris strictinervis represents upper and terminal portions 

 of the frond and compound pinnae. Cladophlebis alata is the form found 

 lower down. The larger pinnules of the fossil represented in PI. XXXIX, 

 Fig. 9, are forms establishing a passage from the alata to the strictinervis 

 type. Most of the specimens belong to the strictinervis type, and none 

 with dentation so pronounced as that in C. alata were found. Some of 

 the pinnules of Pecopteris strictinervis, as seen in the Virginia Potomac, 

 show a toothing similar to that found in the form depicted in Fig. 3. 

 The following description of the fossil may be given : 



The plant was probably arborescent with strong rachises and wide 

 spread of foliage. The epidermis seems to have beeji firm and durable, 



